A weapons such as a rifle or a pistol is sometimes provided with a telescopic sight using refractive (or reflective) optical components to form a magnified and/or intensified image of a target. The telescopic sight is typically formed with a group of lenses in a sight housing. The lenses may be fixed in position relative to each other for a fixed magnification, or may be controllably movable to achieve a controllably variable magnification. The sight housing is affixed to the upper side of the barrel of the weapon and generally aligned with the boresight of the barrel. The sight is thereafter precisely aligned using adjustments to the sight during actual or simulated live firing exercises, a process sometimes termed “sighting in”. Once precisely aligned, the sight is used for highly precise aiming of the weapon during service.
One of the problems experienced with the conventional telescopic sight is that its field of view is reduced proportionately with its increasing optical magnification of the target. That is, a sight with a magnification of 10× has a field of view of about half that of a sight with a magnification of about 5×. For some applications, this reduced field of view is acceptable, but in other applications such as military and police applications the reduced field of view is particularly disadvantageous because it increases the difficulty and time for the user to visually acquire the target. The reduced field of view also reduces the situational awareness of the user, so that the user peering through the sight becomes unaware of events near the target but outside the field of view.
The usual approach to achieving an increased field of view for a selected optical magnification is to increase the diameter of the lenses and the diameter of the sight housing. Large-diameter sights may be tolerated in applications such as target shooting, where the rifle and the user are in a fixed location and the acquisition time and situation awareness are not of great concern. However, the increase in the diameter of the lenses and of the sight housing increases the bulk and weight of the sight, so that it may become too unwieldy for use in military and police applications, and for hunters.
There is a need for an improved approach to sighting systems to provide increased magnification of the target, while at the same time maintaining a good field of view and situational awareness for the user. The present invention fulfills this need, and further provides related advantages.